def a(n):
    for i in range(1,n+1):
        print('\t'*(n-i),sep='',end='')
        print(*range(i, 0, -1), sep='\t')
    print('-'*10)
    for i in range(n,0,-1):
        print('\t' * (n - i ), sep='',end='')
        print(*range(i,0,-1),sep='\t')
a(12)

# 试试不用\t保证空隔宽度一致
